[Antennas] gain vertical

Fri Apr 22 14:37:32 EDT 2005

Great that your home constructed antenna is working great.
I am assuming that the gain is referenced to an isotropic radiator which is 
truly an omni directional antenna, not just in azimuth but in elevation, a 
spheroid comes to mind as far as a visual representation of the istropic 
pattern. You hit on the answer your antenna has a dough-nut pattern and 
since it is collinear further gain is obtained in the elevation pattern, 
your dough-nut has been flattened, giving you increased radiation in the 
lower elevation angles and less at the higher.
73, Jim de wd4air
>From: fkamp at comcast.net
>To: "antennas at mailman.qth.net" <antennas at mailman.qth.net>
>Subject: [Antennas] gain vertical
>Date: 2005年4月22日 12:30:31 -0500
>>I just built and installed a vertical collinear for 2 meters. Two half
>waves.
>>It is touted to be an omnidirectional gain antenna. This thing works
>well. Much better than the 1/4 wave ground plane I was using at the
>same elevation.
>>Then I got to wondering. I understand how a beam works. You get gain
>in one direction because the signal is 'directed' toward the favored
>direction.
>>I am not sure where the gain comes from in a vertical gain antenna. It
>is still omnidirectional. Seems the only thing it plays with is
>take-off angle. I dont see how that translates to gain.
>>Regards,
>Frank Kamp
>K5DKZ